ceph: trivial buildbot warnings fix

The linux-next build bot found a three of warnings, this addresses all of them.

 * non-ANSI function declaration of function 'ceph_fscache_register' and
   'ceph_fscache_unregister'
 * symbol 'ceph_cache_netfs' was not declared, now it's extern in the header.
 * warning: "pr_fmt" redefined
Signed-off-by: Milosz Tanski <milosz@adfin.com>

fs/ceph/cache.c

@@ -21,8 +21,6 @@
  *
  */
 
-#include <linux/fscache.h>
-
 #include "super.h"
 #include "cache.h"
 
@@ -56,12 +54,12 @@ static const struct fscache_cookie_def ceph_fscache_fsid_object_def = {
 	.get_key	= ceph_fscache_session_get_key,
 };
 
-int ceph_fscache_register()
+int ceph_fscache_register(void)
 {
 	return fscache_register_netfs(&ceph_cache_netfs);
 }
 
-void ceph_fscache_unregister()
+void ceph_fscache_unregister(void)
 {
 	fscache_unregister_netfs(&ceph_cache_netfs);
 }

fs/ceph/cache.h

@@ -26,6 +26,8 @@
 
 #ifdef CONFIG_CEPH_FSCACHE
 
+extern struct fscache_netfs ceph_cache_netfs;
+
 int ceph_fscache_register(void);
 void ceph_fscache_unregister(void);